The purpose of this study is to determine the genetic basis of Fanconi anemia (FA), an autosomal recessive disorder characterized by diverse congenital abnormalities, and a predisposition to bone marrow failure and malignancy, particularly acute myelogenous leukemia (AML The specific objectives of this project are: (1) To identify mutations in the genes for FA complementation group A (FA-A) and group C (FA-C) and other FA genes when they are isolated, and to make genotype-phenotype correlations; (2) To develop screening methods using DNA technology, for FA diagnosis and carrier detection. (3) To isolate and clone other FA genes by a combination of positional and functional complementation; (4) To study the structure and expression of these other genes. A major resource and unique feature of this proposal is our access to a large number of patients with FA exhibiting the full spectrum of its diverse features, through the International Fanconi Anemia Registry (IFAR) maintained by us at the Rockefeller University. This provides us with phenotypic information on FA patients as well as a source of cells for molecular studies; we currently have DNA samples from a total of 422 patients affected with FA. Understanding the genetic defect in FA should lead to a better understanding of birth defects and cancer predisposition in general, and the interaction of genetic and epigenetic factors in their pathogenesis. Mutation screening will initially be performed by sizing PCR amplified fragments from cDNA, by genomic DNA blot hybridization and by restriction endonuclease fingerprinting (REF). As mutations are characterized at the genomic level and sequenced, ARMS assays will be developed to permit rapid DNA based screening methods for (1) assignment of FA patients to complementation group, (2) prenatal diagnosis in FA families, and (3) identification of carriers in FA families and in populations at risk. It is an objective of this project to extend our ability to define the FA genotype of all patients and to make genotype-phenotype correlations. This would enable physicians to better predict clinical outcome and aid decision-making regarding major therapeutic modalities for this clinically heterogeneous disorder. A positional cloning approach will be used to clone the FAB and FAE genes, made feasible by the detailed physical mapping information that is rapidly becoming available through the Human Genome Project. Linkage analysis will be used to map these loci; cDNAs will be isolated by direct selection from cosmid contigs from the appropriate region. This will be combined with functional complementation in an effort to accelerate the identification of these genes.